Ten years ago today, the Opportunity rover landed on Mars. In this newly released retrospective, NASA engineers reflect on the challenges they've faced keeping this intrepid little rover roving well beyond its original 90-day mission.

There are no vehicle repair stations on Mars. The Opportunity rover landed on the Red Planet in January 2004 for a 90-day mission. Ten years later it's still going strong despite not being serviced by human hands in over a decade. The engineering team discusses the demands of driving a rover millions of miles away, keeping it alive in the extreme Martian elements and doing long-distance repairs.

It's important to remember that Opportunity didn't make the trip to Mars alone; Spirit led the landing charge, touching down on the opposite side of the Red Planet three weeks ahead of its twin. The two of them have conducted some incredible science in their tour of duty (even if we lost contact with Spirit back in March of 2010):